add test cases for the new transformer

Signed-off-by: Aramis <sennyeyaramis@gmail.com>
Signed-off-by: aramissennyeydd <aramis.sennyey@doordash.com>

plugins/catalog-backend/src/modules/core/policyToProcessorTransformer.test.ts

@@ -0,0 +1,90 @@
+/*
+ * Copyright 2024 The Backstage Authors
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+import { Entity, EntityPolicy } from '@backstage/catalog-model';
+import { policyToProcessorTransformer } from './policyToProcessorTransformer';
+import { clone } from 'lodash';
+
+describe('policyToProcessorTransformer', () => {
+  const entityToProcess: Entity = {
+    apiVersion: 'backstage.io/v1alpha',
+    kind: 'Component',
+    metadata: {
+      name: 'test',
+    },
+  };
+  it('modifies the entity if the policy modifies the entity', async () => {
+    const policy: EntityPolicy = {
+      async enforce(entity) {
+        entity.kind = 'Group';
+        return entity;
+      },
+    };
+    const processor = policyToProcessorTransformer(policy);
+    const clonedEntity = clone(entityToProcess);
+    const entity = await processor.preProcessEntity?.(
+      clonedEntity,
+      {} as any,
+      jest.fn(),
+      {} as any,
+      {} as any,
+    );
+    expect(entity).toBeTruthy();
+    expect(entity?.kind).toBe('Group');
+    expect(entity?.apiVersion).toBe('backstage.io/v1alpha');
+    expect(entity?.metadata.name).toBe('test');
+  });
+
+  it('does not modify the entity if the policy returns undefined', async () => {
+    const policy: EntityPolicy = {
+      async enforce() {
+        return undefined;
+      },
+    };
+    const processor = policyToProcessorTransformer(policy);
+    const clonedEntity = clone(entityToProcess);
+    const entity = await processor.preProcessEntity?.(
+      clonedEntity,
+      {} as any,
+      jest.fn(),
+      {} as any,
+      {} as any,
+    );
+    expect(entity).toBeTruthy();
+    expect(entity?.kind).toBe('Component');
+    expect(entity?.apiVersion).toBe('backstage.io/v1alpha');
+    expect(entity?.metadata.name).toBe('test');
+  });
+
+  it('bubbles up processor error', async () => {
+    const policy: EntityPolicy = {
+      async enforce() {
+        throw new TypeError('Invalid value for metadata.name');
+      },
+    };
+    const processor = policyToProcessorTransformer(policy);
+    const clonedEntity = clone(entityToProcess);
+    await expect(
+      processor.preProcessEntity?.(
+        clonedEntity,
+        {} as any,
+        jest.fn(),
+        {} as any,
+        {} as any,
+      ),
+    ).rejects.toThrow(/Invalid value for metadata.name/);
+  });
+});

plugins/catalog-backend/src/modules/core/policyToProcessorTransformer.ts

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+/*
+ * Copyright 2024 The Backstage Authors
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+import { EntityPolicy } from '@backstage/catalog-model';
+import { CatalogProcessor } from '@backstage/plugin-catalog-node';
+
+/**
+ * Transform a given entity policy to an entity processor.
+ * @param policy The policy to transform
+ * @returns A new entity processor that uses the entity policy.
+ */
+export function policyToProcessorTransformer(
+  policy: EntityPolicy,
+): CatalogProcessor {
+  return {
+    getProcessorName() {
+      return policy.constructor.name;
+    },
+    async preProcessEntity(entity) {
+      // If enforcing the policy fails, throw the policy error.
+      const result = await policy.enforce(entity);
+      if (!result) {
+        return entity;
+      }
+      return result;
+    },
+  };
+}